2011 Porsche 911 GT3 R Hybrid 2.0

Ferocious, frugal, and a glimpse into Porsche's hybrid future.

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It's my birthday, and I had to work—and that was the best present ever. In this case, work meant skipping out on the Halloween parties for a trans-Atlantic flight to Portugal to test drive the appropriately pumpkin-colored Porsche 911 GT3 R Hybrid at the Circuito do Estoril. My friends say they hate me; I'm okay with that.

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The Porsche factory development team was on hand to prep me for the once-in-a- lifetime experience of lapping the prototype race car at speed. Unlike the Porsche 911 GT3 Cup, or RSR, the Hybrid is not sold; it is purely a technology demonstrator and rolling test lab. That someone other than a Porsche factory driver is allowed to turn the wheel is a big deal, and also an indicator that there is a new car in development to replace it. Even the engineer responsible for Motorsport Development-Performance, Owen Hayes, hasn't driven it. And he's the guy explaining to me how the steering wheel's 14 buttons and 6 knobs can adjust this all-wheel-drive hyper-drive hybrid from stable and predictable, to well...not. I try to remember the location of each knob and button, because I'm not going to take my eyes off the road in this $1 million test car.

Mr. Hayes twirls his finger at me and I take a deep breath, which is challenging as I'm wedged into an OMP race seat complete with HANS device and 6-point Schroth belts. I press the start button. The chassis shivers to life like a wet dog fresh from a bath. Foot still on the clutch, I pull the intricately machined shift paddle with the fingers of my right hand. The large N displayed on the wheel switches to a 1. The red HYBRID MAP knob is set to 10, which means the system is off—unless I press the REKUP button to start manually charging the flywheel, or press the BOOST button to send power to the front wheels. In this mode, the Hybrid is purely a rear-drive Porsche GT3 R with 470 horsepower on tap from a 4.0-liter flat-6 race engine that makes earplugs an absolute necessity. I slowly let the clutch out to gracefully leave the pits without laying rubber.

To the amusement of everyone, I stall it. This wasn't unexpected. I've learned from driving a Porsche Cup car that finding the engagement point is a right of passage. Once found, the car chugs forward, and unlike in a Cup car, I won't need the clutch again until I come back to the pits. All shifting of the dog-box 6-speed sequential is done via the paddles on the back of the custom steering wheel, made in-house for an estimated 5000 euros. A mechanical whine and gear lash resonate in the cabin, somewhat overshadowing the raucous flat-6. Not your everyday 911 here.

With the pit lane speed limiter enabled I'm held at 35 mph in 2nd gear. I'm a habitual left-foot braker, so I take this time to shift my foot off the clutch and acclimate it to hovering over the massive brake pedal. Two feet fit on it comfortably. Interestingly, factory driver Jörg Bergmeister told me that the team prefers drivers to right-foot brake as it improves fuel economy.

I'm not concerned with economy right now, and focus on entering the Estoril race track. I'm only a bit familiar with the course, thanks to YouTube videos and two laps in the passenger seat of a Carrera 4S piloted by Jörg. I think I know maybe two of the track's 13 corners. Adrenaline flows and my nerves are lit up like the steering wheel's shift lights. The engine tune we're running today is allowing a redline of just over 9000 rpm and the majority of a lap is spent above a frantic 7000 rpm.

Some of the stickiest Michelin rubber on the planet is beneath me. I'm cautious in the slightly damp conditions, but find the lateral grip superb. The (30/65-18 front, 31/71-18 rear) Michelin race slicks allow a staggering 1.5g of lateral grip, and that's not a peak reading. This type of grip takes some getting used to, and I find myself progressively probing the limits and routinely coming up short in braking distance and corner entry speed. Better this than the alternative I suppose, but the car is capable of so much more. I think an entire day of lapping would be needed to acclimate.

The fun truly begins as my radio clicks on and I'm instructed by Hayes to select HYBRID MAP 9. I feel for the red knob, visually check that I have the right one, and give it one click down. A slight deceleration is induced as the electric motors on the front axle create drag while generating the electricity needed to spool up the 30.9-lb. flywheel/motor in the passenger floor space. To allow for all-wheel drive, the front hubs are borrowed from a Panamera and have roughly a 6:1 gear reduction to the electric motor. Once the flywheel is up to 28,000 rpm, the onboard display reads 0 charge. A full charge of 100 requires 36,000 rpm. Without hearing protection, the 500-Hz hum of the system is deafening. It's also surprisingly smooth, producing a mostly unnoticeable vibration.

That's amazing, when considering that the spinning mass is rigidly mounted to the chassis with a massive carbon-fiber backing plate for safety. If the flywheel fails, it will disintegrate into carbon dust inside the robust housing, while glass windows under it allow excess pressure to vent. This is to prevent the driver from being covered in a dust that resembles carbon-fiber brake rotor dust. (If you've ever seen a brake failure in an F1 race, you'll know why Porsche wants to keep that stuff out of the cabin.) If something less catastrophic happens, such as a software glitch, the system can easily be rebooted while the car is in motion, or it can be disabled and de-coupled. This is accomplished via electronic clutches integrated into the gear reduction of the two front electric motors.

Ignoring those contingency plans, I approach the main straight's braking zone at 155 mph. I hit the big middle pedal and decelerate at just over 1g, slowing to 47 mph for turn 1. A quick check of the State of Charge lights and it's clear I've generated flywheel energy. The SOC indicator looks like shift lights, but is below the digital display—it's now at about 90 percent.

The simple act of braking for turn 1 needs some explanation, as the brake pedal controls both hydraulic and regenerative braking systems. The brake pedal travel is slightly longer than that of a conventional race car. Front to rear balance is handled with a conventional brake balance bar on the pedal and adaptive ABS. When my foot first hits the brake the pedal sinks slightly until it hits something rock hard. In a standard race Porsche, the pedal is typically rock solid on the first touch. Pressure on the pedal determines deceleration, but the hybrid system wants that energy and thereby invokes the electric motors as generators. They begin immediately to absorb energy and spin up the flywheel. This means the hydraulic system needs less brake pressure to keep the braking force constant, so it pushes the brake pedal back slightly to unload the hydraulic system a commensurate amount. My pedal effort never changes, but I can feel through my foot the system kick in with a click. Nothing intrusive, mind you, but it lets you know that it's working. Although the braking was phenomenal I wasn't overly aggressive, seldom finding ABS. Bergmeister, however, told me that to be competitive it must be used.

As is road-going hybrids, braking energy-regeneration puts less stress on the front brakes and so they last longer. This allows the 911 Hybrid race car to use lighter brake rotors if desired. In this case we're running the thinner sprint rotors that were on the car at Mazda Raceway Laguna Seca for the 6-hour enduro.

Finding a Rhythm

But I digress. Hitting turn 1's apex with the flywheel near its maximum 36,000 rpm I'm charged (pun intended) for my first all-wheel-drive corner exit. I don't have to hit the boost button to activate it, it's pre-programmed for this track knowing approximate location on the track based on driven distance since it last crossed the start-finish line. I just have to hit the go pedal and it will apply the front power specific to that corner. Although adjustments can be made on the steering wheel to alter these settings, I'm not prepared to do that right now. I tip into the throttle and before I know it I'm snapping through the gears as the shift lights illuminate. I didn't even feel the front wheels working. It wasn't until the tight uphill right hand turn 3 that I felt the slight tug on the steering wheel that indicates the front axle putting power down. Before I had to be a little patient mid corner; now I can feel the twin 100-hp electric motors pulling the nose around, allowing me to use the right pedal sooner.

The electric motors act independently on each wheel, and allow for torque vectoring. The exact amount is determined by the software, but it can also be tuned by the driver with the two yellow knobs at the bottom of the steering wheel, labeled TV IN and TV OUT. Regenerative braking can torque vector as well, so the system can drastically change how the car behaves on corner entry as well as exit. The EV MAP knob adjusts the ramp-up of power delivery by the electric motors. Bergmeister says he likes being able to adjust the car's driving attitude without having to enter the pits, but points out that the system still can't overcome worn tires.

I find that an already well balanced and ultra responsive race car has become easier to drive. The stabilizing factor of all-wheel drive on corner exit is obvious, and the ability to put down another 200 horsepower at the front wheels makes the GT3 R Hybrid quicker out of corners. With a good flywheel charge, corner exits become violent and like turbo boost—addicting. But this is also where the Hybrid concept has its detractors. At best there is 6 to 8 seconds of boost to be had, with actual boost ebbing and flowing between corners, no two ever the same. Actual availability of boost is determined by the engineers and selected hybrid map. On the previous generation of the car, Version 1.0, the drivers made those determinations and all did it differently.

To better optimize efficiency, the drivers are restricted to adjusting the lower four knobs on the steering wheel. The ENGINE MAP and TC MAP knobs are to be changed only by command of the race engineer. The driver focuses on going as quick as he can, while the engineers adjust the car to optimum frugality. When applied to endurance events such as the 6-hour ALMS race at Mazda Raceway Laguna Seca, this very car ran about 5 percent more efficiently than the competition. This means the Hybrid pitted three times compared to five for the competition, which allowed the car top dominate the GT class, although it was not competing for points. In endurance racing, having to make fewer pitstops is a huge advantage, particularly when you're still capable of running fast laps.

The GT3 RSRs that make up the Porsche GT field in the ALMS are the fundamental basis for the Hybrid, and the team had tried hard to build parity between the two models to create a better comparison. Racing against oneself is a sure way to find room for improvement. Version 2.0, the car I drove, is 110 lb. lighter than the previous Hybrid, thanks to a consolidation of the hybrid system and the removal of many extraneous body modifications. Stock GT3 R bodywork is used, and the side air vents and louvered fenders of its predecessor are not needed. A new water-to-oil cooler keeps the flywheel's ceramic bearings at a cool 158 degrees F. That same water cools the power electronics and motors, via a radiator located in front of the conventional one for the engine.

Overall, Version 2.0 of the Hybrid (2866 lb.) still carries an extra 220 lb. compared to the 2646-lb. GT3 R race car from which it's derived. The majority of that extra weight is over the front axle, providing a more even weight distribution compared to a typical 911. Not surprisingly, this has necessitated larger front tires, 30/65-18 compared to 27/65-18 on the GT3 R.

All told, the hybrid system, by itself, adds 331 lb to the GT3 R, but creative engineering has helped the team shed 110 lb. in other places. Two examples: the 12-volt lithium-ion battery is borrowed from the RS Spyder, and the roof is made of magnesium and is 11 lb. lighter than the steel one it replaces. Of note, the exotic roof came from Porsche R&D, which experiments with alternative materials.

As I clip apexes and drive more confidently out of each corner, it's easy to imagine myself doing a 1-hour stint. Unfortunately, my time is up much too soon. Like going to Disneyland on your birthday, the best rides end too quickly. Hayes gets on the radio, telling me to select HYBRID MAP 11 and begin discharging the flywheel system on the cool-down lap. The frenzy is over, and I take a moment to finally blink.

At dinner, I bring up a spy photo of a street-going GT3 with Hybrid 1.0 bodywork, shot at a gas station in Germany. According to Daniel Armbruster, manager Motorsport Development –Systems, that is the car used by System Engineers Christoph Seelbach and Jens Maurer to tweak the hybrid drive software. Its flywheel is mounted where the rear seats would be, which allows a passenger seat. While one engineer drives, the other adjusts the programming on a laptop using Simulink software from MathLab. This way, the team can rapidly make changes.

We'd love to see a version of this flywheel hybrid system in a street car, but there are some challenges. The first is noise and vibration from the flywheel—the hum it makes is like that of a turbine engine on a jet liner. That's fine for a race car (say, a future 918), but obnoxious in a street car. That said, a Porsche board member has driven the car and liked it, so I'm hopeful that the team's denial of this technology being used in a street car is all a ruse. Next year, when the GT3 variant of the new 991 chassis is introduced, I hope to see a hybrid option. Never thought I'd say that...